Patent Literature 1 describes an electronic device, such as a mobile phone, that transmits air conduction sound and bone conduction sound to a user. Patent Literature 1 also describes that the air conduction sound is sound perceived by an auditory nerve of a user as a result of an eardrum being vibrated by an air vibration that is created by a vibration of an object and that travels through an external auditory canal down to the eardrum. Patent Literature 1 also describes that the vibration sound is sound perceived by an auditory nerve of a user through a part of the body (for example. Cartilaginous portion) of the user which contacts with the vibrating object.
In the mobile phone described in Patent Literature 1, a rectangular plate-shaped vibration body configured by piezoelectric bimorph and a flexible material is attached to an outer surface of a housing by way of an elastic member. Patent Literature 1 also describes that, upon application of a voltage to the piezoelectric bimorph of the vibration body, the piezoelectric material is expanded and contracted in a longitudinal direction, thereby causing the vibration body to undergo flexture vibration. As a result, when the user places the vibration body in contact with an auricle, air conduction sound and vibration sound are transmitted to the user.
Patent Literature 2 describes an electronic device, such as a mobile phone terminal, that vibrates a panel due to deformation of a piezoelectric element attached to the panel, to thereby transmit human-body vibration sound to an object that is in contact with the panel.